Automatic rhythmic chording unit

ABSTRACT

A keyboard musical instrument is provided having a keyboard for playing solo or lead. Automatic switching also is provided for producing predetermined percussive-type rhythm patterns and sounds, and is operable with a plurality of chord buttons to play predetermined chords and also a related bass note. The chords and bass note may be alternated, the bass note being the root of the chord or its fifth preferably alternating.

United States Patent Arsem et al. 1 Dec. 19, 1972 [541 AUTOMATIC RHYTHMIC CHORDING 3,422,210 1/1969 Choshi Enya =1 a1. ..84/D1G. 22 x UNIT 3,435,123 3/1969 Schrecongost ..84/DIG.23X 3,476,866 11/1969 Cunningham ..84/1.26 1 Alvin Clarence; Harold 3,255,292 6/1966 Park"... ..s4/1.03 0. Schwartz; Anthony C. Ippollto, 3,358,068 12/1967 Campbell ..84/1.03 both of North Tonawanda, all of 3,548,066 12/1970 Freeman ..84/l.03 N.Y.

OTHER PUBLICATIONS Th W litz [73]. Asslgneel m e W er Company Chlcago Pages 191-194, lntroducnon to Electronlc Systems, Circuits, and Devices," Pederson, Studer, Whinnery, [22] Filed: June 17, 1971 McGraw-ill Book Co., N.Y. 1966 [21] Appl' l54054 Primary Examiner-Lewis H. Myers Assistant Examiner-U. Weldon [52] US. Cl. ..84/ 1.03, 84/ 1.13, 84/ 1.17, Attorney-Olson, Trexler, Wolters and Bushnell 84/l.24, 84/1.26 [51] Int. Cl ..Gl0f 1/00 ABSTRACT [58] Field of Search ..84/l.01, 1.03, 1.24, 1.26, A keyboard musical instrument 5 provided having 3 m DIG-23 keyboard for playing solo or lead. Automatic switching also is provided for producing predeter- 1 g References cued mined percussive-type rhythm patterns and sounds, UNITED STATES PATENTS and is operable with a plurality of chord buttons to play predetermmed chords and also a related bass 3,567,838 3/1971 Tennes ..84/1.03 X note. The chords and bass note may be alternated, the 3,546,355 12/1970 Maynard ,.84/1.03 bass note being the root of the chord or its fifth 3,585,891 6/1971 Schwartz et 8|. ..84/1.03 Preferably altemating 3,207,952 9/1965 Brahm ..84/D1G. 23 X 3,590,129 6/1971 Freeman ..84/D1G. 22 X 4 Claims, 5 Drawing Figures 60 J'U'U'L/ PATENTED DEC 1 9 m2 3 7'06. 837

sum 3 or 5 Nww I1.

1 AUTOMATIC RHYTIIMIC CHORDING UNIT Electronic organs have enjoyed considerable commercial success and popularity in recent years. Although it is not particularly difficult to learn to play an electronic organ, there are those who do not have the time or the inclination to learn to play, using the left hand as well as the right and one or both feet in conventional manner, as for playing chords and bass notes. Heretofore, there have been electronic chord organs developed wherein a plurality of buttons is provided, each of which ispushed to play a preset chord. Conventionally, each chord is held on until the chord changes, and the player then pushes another chord button. This is remarkably easy to master, but in relatively short order becomes rather monotonous. Accordingly, chord organs of the aforesaid type have fallen out of favor.

Electronic switching techniques have now been advanced to apoint where rhythm devices are well known in the patent art and in the market place. A master clock, a series of dividers, and a matrix or other combining network or devices provide substantially any desired rhythm pattern. Electronic waves corresponding to various percussive tones such as drums, cymbals, etc. are keyed or gated in accordance with the foregoing combination to provide the desired tones.

In accordance with the present invention, such electronic switching is utilized to provide not only percussive rhythm tones, but to play selective chords and related bass notes alternatively.

In accordance with the present invention, a plurality of oscillators is provided to produce the notes necessary for chords in at least three or four basic musical keys. A timer or clock and logic devices of known construction are used to key the selected chords on and off in accordance with pre-set rhythm patterns. The logic devices further may alternate the chord played with the root and/or fifth of the chord. At the same time, the clock and logic devices control the playing of rhythm sounds such as bass drum, snare, block, cymbal, and brush, along with the playing of the chords and ba notes.

The invention will be best understood with reference to the following description when taken in connection with the accompanying drawings wherein:

FIG. 1 is a block diagram showing a simplified form of the invention;

FIG. 2 is a block diagram showing a somewhat more complex form of the invention as incorporated in an electronic organ and using the generators thereof;

FIG. 3 is an electrical wiring diagram showing certain details of FIG. 2;

FIG. 4 is another electrical wiring diagram showing additional details; and,

FIG. 5 is yet another electrical wiring diagram showing a system for the playing of chords without automatic rhythm.

Turning now to FIG. 1, there will be seen a basic timer or clock 10. This clock and the ensuing parts now to be described are generally similar to those disclosed in Harold 0. Schwartz, Peter E. Mah er and John E. Holt application for U. S. Pat., Ser. No. 827,234, filed May 23, 1969 for An Electronic Ryhthm Generator Particularly Suitable for Integrated Circuitry (prosecution on the merits having been closed by a communication from the Examiner Nov. 2, 1970) to which reference maybe made if it is desired to ascertain the circuits accompanying the block diagrams shown herein. The clock I0 is connected to a primary logic unit 12 which in turn is connected to rhythm pattern gates 14.

A plurality of percussion frequency generators 16 is provided, such, for example, as for bass drum, snares, etc., and these percussion frequency generators are connected to frequency gates 18 which are controlled by the rhythm pattern gates 14 as indicated. The outputs from the frequency gates 18 are connected to percussion voice filters 20. In addition, a white noise generator 22 is provided which is controlled by the rhythm pattern gates to simulate the sizzle sound of a cymbal. The output of the noise generator .22 is likewise connected to the percussion voice filters. The output of the percussion voice filters is connected to a rhythmpattern selector 24, which is connected back to the rhythm pattern gates 14 to control the operation of these gates, all in accordance with the previously identified application Ser. No. 827,234. The output of the rhythm pattern selector is connected to a collector bus 26 which is in turn connected to a mixer and preamplifier 28 leading to an amplifier 30 having a low impedance output whereby the output of this amplifier can be connected to any suitable power amplifier and loudspeaker connection.

A power supply 32 is indicated at the lower left corner of the drawing, and this is suitably connected to the parts heretofore enumerated, and those to be set forth hereinafter. d 4

In addition to the production of rhythm sounds in accordance with the block diagram as heretofore outlined, and which corresponds to application Ser. No. 827,234, as noted heretofore, means is provided for the automatic playing of chords and accompanying bass notes. Thus, there is provided a series of stable oscillators 34. By way of illustration, there are 12 such oscillators, and these are LC (inductance-capacitance) oscillators producing a square wave output. Suitable means is provided for connecting pre-selected ones of the oscillators to a chord output 36, and in a simple case this may be push buttons 38 and accompanying switches. Alternatively, and for more skilled instrumentalists, there could be provided 12 push buttons or keys, one for each of the oscillators, with the player to depress desired ones of the push buttons or keys to select the chord himself. In any event, the output of the oscillators is in the form of square waves, as indicated above the output line 36, which are rich in harmonics, and which can thereafter be filtered as desired to produce proper instrumental tones. The chord output 36 is connected to a chord unit and wave shaper 40 about which more will be said shortly.

In addition .to the plurality of outputs corresponding to a chord, the oscillators '34 are provided with a single bass output 42 which corresponds to the frequency of the root note-of the chord being played, and also to the musical fifth related to this root note. The output 42 is likewise connected to the chord units and wave shaper 40.

The chord unit and wave shaper includes electronic switches, such as diodes or transistors, and these are controlled by means of suitable connections indicated at 44 from the rhythm pattern gates 14, whereby to 3 produce a chord output 46 leading to a chord straf unit 48,- the chord output 46 being pulsed in accordance with the timing and pattern in which the rhythm pattern gates I4are controlled by the primary logic unit 12 and the rhythm pattern selector 24. As will be apparent,

this is in timed relation-to the rhythm sounds, includingthe percussive tones of the frequency generators 16 and the sizzle or cymbal-like tones from the noise generator 22.

In addition, the a pulsed output of the root note at 50 and of .the musical fifth related theretoat 52. Both of these are connected to a bass divider 5.4, which divides the root and fifth tones by two.

A control arm 56 leads from .the rhythm pattern gates 14 to the bass divider circuit'54 to control the outputthereof, consisting of the root and the fifth note alternating, and applied at 58 to a bass keyer and shaper 60. The bass keyer and shaper 60 is controlled at 62 from the line 56 so'that properly shaped oscillationscorresponding to the root or fifth note areapplied to a bass straf unit 62. Both straf units 48 and 62, which may include such preamplification as may be necessary, further voicing, switching, etc., are, connected'to the collector bus 26 for amplification to the mixer and preamp along with the rhythm tones supplied thereto.

Thus, in accordance with the invention as disclosed to this point, rhythm tones are produced in any desired pattern, such as waltz, swing, Latin, etc., while chords and bass notes are played in timed relation thereto. Preferably, the control from the rhythm pattern gates 14 is such that the" bass and the chords altemate, as is common in musical playing, as for example, in playing an electronic organ. Furthermore, preferably the root and fifth notes are played alternately, although this is not an essential. The melody accompaniment may be played on an entirely separate instrument, or the invention as heretofore shown and described may be packaged with any satisfactory instrument, such as a conventional electronic organ.

The concepts as heretofore shown and described are combined with an electronic organ with a more efficient use of tone generators as is shown in FIG. 2, to

' which reference should now be made. Much of the disclosure in FIG. 2, is the same as in FIG. 1, and like numerals are utilized with the addition of the suffix a to identify similar parts. What distinguishes the disclosure of FIG. 2, from that of FIG. 1, is that it utilizes certain of the existing parts of an electronic organ. More specifically, there will be seen at the upper left hand corner a block representation of 12 LC (inductancecapacitance) oscillators 64 corresponding to the top octave of the organ tones. As is commonpractice in electronic organs, the master oscillators are connected to strings of divider oscillators 66. Typically, there are 12 parallel strings of three divide-by-two dividers, thus providing four octaves of organ tones. Square waves are provided in each instance to be filtered as is needed. Since square waves are available of a great many frequencies, it is not necessary to provide specific percussion frequency generators such as was done in FIG. I. Instead,'selected outputs are taken at 68 which are supplied tothe frequency gates 18a. Likewise, bass 42a and chord 36a outputs are taken from the dividers 66 to the chord unit and wave shaper 40a. As will be chord unit and wave shaper produces 7 apparent far more frequencies are available than the 12 of FIG. 1. Accordingly, the chord unit and wave shaper 40a preferably is provided witha chord button board providing all of the common chords i n major, minor, and seventh, with separate buttons for the bass. In playing, the thumbmay press a bass button corresponding to a particular bass note of a chord, while a finger of the left hand engages the corresponding-chord button. The bass note, either root or fifth, preferably alternating, is provided alternating with the chord asdiscussed-with regard to FIG. 1. Y In addition to the foregoing, the dividers 66 (and also the 12 master oscillators 64) have an output at 70 controlled by an organ'keyboard 72 for playing of a solo or melody, the keying conveniently being audio keying. According to the manner in which the switching is produced, controlled in part by a solo straf unit 74 to which the keyboard solo audio keys 72 are connected, the square waves may pass through for filtering to produce one type of tone, orthe square waves may be combined with one another in staircase fashion to simulate sawtooth waves which produce a characteristic type of tone. g

The solo straf unit '74 is connectedto the collector bus 26a along with the bass straf and the rhythm pattern selector as heretofore. The output amplifier a is connected to an organ amplifier 76 which in turn is connected to a loudspeaker system 78, whereby the organ solo notes and also the rhythm effects, chords, and bass notes are played simultaneously. Although not specifically shown it will be understood that the organ may retain the lower or accompaniment manual and the pedal clavier, and the tonal outputs therefrom may be connected through the same organ amplifier 76 and loudspeaker system 78, or through a different amplifier and loudspeaker system." a v Details of certain of the parts referred to in FIG. 2, will be seen with reference to FIG. 3. Thus, the bass input from the chord unit, of which more will be set forth later with regard to FIG. 4, is identified at 80 in the upper right comer of FIG. 3. When a bass signal is applied to a driver circuit 82 comprising a transistor buffer amplifier and a direct coupled transistor amplifier stage 85, the output of which is applied to a divideby-two divider 86. The divider is provided with DC potential, as indicated, on one terminal, and is grounded in another terminal. The output from the amplifier 85 is connected to a third terminal, while the output is taken at a fourth terminal, the output being a square wave as indicated at 88. The square wave is positive going, and is normally blocked by a diode 90, except when the diode is forward biased, as will be brought out hereinafter;

When the diode is openit is on a decaying basis, I

the bass square wave oscillations conducted thereby being shown at 92. The decaying square wave 92 is applied to a transistor amplifier stage 94, and the output thereof is taken on a line 96 leading to the bass straf unit 62a.

The chord signal from the chord switchboard, about which more will be said later in connection with FIG. 4, is applied to the circuit of FIG. 3, at 98 which leads to a transistor amplifier and mixer stage 100. The signal from this stage 100, the envelope of which is indicated 102, is applied to the output lines 96, and it will be appreciated that in the particular example of FIG. 3, the chord straf and bass straf units are combined.

The bass input line 80 is provided with a branch line a 104 leading to the upper left corner of FIG. 3, to the input of a two transistor switching circuit 106. The input of the switching circuit 106 includes a shunt capacitor 108 connected to the base of a first switching transistor 110. The output of the switching transistor 110 is connected to the base of a second switching transistor 112, and the output of the second switching transistor 112 is connected through a resistor 114 to the anode of the diode 90. In the absence of a bass signal from the line 80 and from the branch line 104, there is no charge on the capacitor 108 and the transistor 110 is biased off, the transistor 112 thereby being biased on. With the transistor 1l2'biased on, the collector thereof is substantially at ground potential, the anode of the diode 90 therefore likewise being substantially grounded, and the diode being non-conductive of the positive divided bass pulses applied to the cathode thereof.

On the other hand, when the bass signal does appear on the line 80 and the branch line 104, the bass signal comprising positive going pulses, the capacitor 108 charges positive and turns on the transistor 110. This, in turn, turns off the transistor 112, whereupon the anode of the diode 90 is no longer at ground potential, and is at least momentarily at positive potential as will be brought out hereinafter, whereupon the divided bass signal 88 is transmitted by the diode 90 and passes to the transistor amplifier stage 94.

The brass drum pulse train from the rhythm pattern gate 14a is applied to the circuit of FIG. 3, at 116. The bass drum pulse train comprises a succession of negative going pulses, and these are applied to a transistor amplifier 118. The transistor amplifier 118 inverts the negative going pulse train and applies it to a Schmitt trigger circuit 120 comprising transistors 122 and 124. The Schmitt trigger circuit assures the production of pulses of constant amplitude and pulse length which are applied through a diode 126 to a rather large capacitor 128 to charge this capacitor. The capacitor is connected through a resistor 130 to the resistor 114, and hence, to the anode of the diode 90. The capacitor 128 charges rapidly through the diode 126 from the Schmitt trigger circuit stage, but discharges more slowly, partly through a resistor 132 in parallel with the capacitor 128, but mainly through the resistor 130 and 114, and a shunting resistor 134. The diode 126 prevents back discharge of the capacitor 128.

Immediately below the Schmitt trigger 120 as shown in FIG. 3, there is a manual-automatic switch 136. The switch 136 comprises a double pole, single throw switch only half of which is shown immediately below the Schmitt trigger, this half including a grounded fixed contact 138 and a moveable contact arm 140 engageab le therewith. When the moveable contact arm 140 is grounded by engagement with the fixed contact 138, the setting is for manual operation, and the chords and bass notes are played manually on the organ rather than with the automatic rhythm pattern. The moveable switch contact 140 is connected to a junction point 142 which is in turn connected to the cathode of a diode 144 having its anode connected to the collector of the first Schmitt transistor 122. The anode of the diode 144 is also connected to the anode of the diode 146 which connects the collector of the Schmitt transistor 122 to the base of the Schmitt transistor 124. When the switch 136 is in the manual position shown, the base of the Schmitt transistor 124 is grounded, and there is no output from the Schmitt trigger circuit 120, whereby the capacitor 128 is not charged by the Schmitt trigger circuit.

A resistor 150 parallels the capacitor 128 and provides a discharge path therefor to produce the decay on the wave shape 148 shown to the right of the capacitor. The diode 126 provides for rapid charging of the capacitor 128, while preventing back-discharge.

A Schmitt trigger circuit 152 is provided at the'lower central portion of FIG. 3, and comprises a pair of transistors 154 and 156 provided with positive potential through a series resistor 158 over a smoothing capacitor comprising a shunt connected capacitor and resistor 160, the capacitor being of relatively large size. The output of the Schmitt trigger is connected through a diode 162 to a shunt capacitor 164 of relatively large size paralleled by a resistor 166. The diode has its anode connected to the Schmitt trigger circuit and hence is poled to pass positive signalsto the capacitor 164. The diode and the top of the capacitor are connected to an output line 168 leading to the chord switchboard to be described hereinafter in connection with FIG. 4. The output wave shape appearing on the line 168 is shown immediately to the right thereof at 170. This output wave shape comprises a plateau at approximately l7 volts positive potential, the length of the plateau being determined by the pulse width of the Schmitt trigger circuit. The wave shape then tapers down on a decaying exponential, it being appreciated that the capacitor 164 will charge very quickly through the diode 162, but cannot back-discharge through the diode, the decay time thus being detennined by the resistor 166 in combination with the capacitor 164.

The second pole of the manual-automatic switch 136 is connected to the base of the second transistor 156 of the Schmitt trigger circuit 152. The switch arm 172 is ganged with the switch arm 140, as is indicated, and in the manual position engages a fixed switch contact 174 connected to the base of the transistor 156. Thus, in the manual position the transistor 156 is held off, and no potential is supplied to the switchboard over the line 168. In the automatic position the switch arm 172 does not engage anything, and the Schmitt trigger circuit 152 therefore is free to operate upon application of a positive pulse to the base of the first transistor 154 on a line 176. The pulse, or rather series of pulses, depends upon the selection and keying of signals through a circuit now to be set forth.

The bass drum pulse train after inversion in the transistor inverter or amplifier stage 118, besides being applied to the Schmitt trigger circuit 120, is applied by means of a line 178 to the cathodes of two diodes 180 and 182, the anodes of which are respectively connected to junction points 184 and 186. Since the pulses at this time are positive, they are normally blocked by the respective diodes 180 and 182. However, a connection is made at 188 to the march rhythm switch of a selector 187 (FIG. 3A) so that positive potential is selectively applied to the junction point 184 with the march switch closed, and thus to open the diode gate 180. With the march switch open, ground is applied,

and the diode blocks the signal. Similarly, the Latin switch when closed applies positive potential at 190 to the junction point 186, thereby to open the diode gate 182 when the Latin rhythm is selected, it being appreciated that the selector 187 is ganged with a control for the gates 14a. The junction points 184 and 186 are respectively connected through diodes 192 and 194 to the input line 176 to the Schmitt trigger circuit 152, the anodes being connected to the junction points 184 and 186 so as to conduct signals therefrom to the line 176, thereby providing isolation and preventing a signal at junction 184 from turning on diode 182, and likewise preventing a signal at 186 from turning on diode 180. v t

Rhythm pattern No. 4 from the rhythm pattern gate 14a-is applied to aline 196 (see the aforesaid Schwartz et al. application'Ser. No. 827,234 The rhythm pattern No. 4 comprises a train of positive pulses andis connected by means of the line 196 to the cathode of a directed to the left side where the circuit for the note F is described as illustrative.

The input for the F tone as indicated at the circle 236, is connected through a resistor 238 to the cathode of a diode 240. The frequency oscillations applied are positive going square waves, and hence will not be transmitted through the diode 240 unless the diode is biased on. To prevent leakage a seconddiode 242 is provided in series with the diode 240, the polarity being in the same direction as previously indicated. The anode of the second diode 242 is connected to a junction 244. The junction 244 is connected through a resistor 246 to the anode of the diode 248, the cathode of diode 198, the anode of which is connected to a junc-' tion 200. The junction 200 is connected through a coupling capacitor 202 to the input line 176, and further is connected through a resistor to' the swing switch of the selector 187, whereby the diode 198., comprising a gate, is selectively opened to allow rhythm pattern No. 4 to come through to the line 176.

The block pulse train from the rhythm pattern gates 14a, comprising a train of negative pulses, is applied to a transistor inverter 206 and the resulting positive pulse train is connected through a diode 208 and a resistor 210 to the line 176, previously noted, whereby the inverted block pulse train is applied to the Schmitttrigger The cymbal pulse train from the rhythm pattern gates 14a also comprising a'train of negativepulses, is applied to a transistor inverter stage 212, and the resulting positive pulse train is applied through a diode 214 to the line 176. As-will beapparent, the diodes 208 and 214 provide isolation so that the block pulse train and cymbal pulse train do not have a reaction on one another.

In addition, a positive voltage is applied at 2l6when the'Latin switch of selector 187 is closed and is connected through an isolating diode 218 and a resistor 220 to the anode of the diode 2l4previ0usly mentioned. Similarly, a positive potential is applied at 222 through a diode 224 and the resistor 220 previously mentioned to the diode 124 when the waltz switch of selector 187 is'closed.

Finally, a pedal pulse is applied at 226, consisting of a negative pulse whenever any pedal of the organ is depressed, through a diode 228 to a transistor inverter 230. The resulting series of positive pulses is applied to an isolating diode 232 to the line 176.

The diode 214 is only biased on when one of the diodes 218 or 224 is biased on to prevent undesired interaction at such times as the transistor 212 is conducting (and hence has a low collector-to-base impedance).

Attention now is directed to FIG. 4, wherein there is shown a diode matrix 234 for the chord switching. Frequencies are taken from the frequency divider of an organ and are applied-at inputs indicated by the circles 236 through one octave plus one of notes, indicated as F through F an octave higher. The matrix 234 comprises a plurality of like parts, and attention should be which is connected to a collector line identified at 98, being the same as the input line 98-indicated at the upper right portion of FIG. 3.

The junction point 244 further is grounded through a capacitor 250, and is also connected through a resistor 252 to a connection or tie point 254 indicated as a triangle.

As will be brought out subsequently, a positive voltage is applied selectively. to the tie point F to turn on the diodes 240 and 242, whereby a signal from the input connection 236 may pass through these two diodes, through the resistor 246, and through the resistor 248 to the collector line 98.

As will be understood with reference to FIG. 4, the circuit just described is repeated for each of the octave of notes having the inputs at 236. If it is desired to provide chord inversions, it is possible to supply more than one octave plus one of frequencies to the matrix, in which case the circuit specifically described wouldbe further duplicated.

Immediately to the left of the diode matrix 234 shown in FIG. 4, there is a representation of a chord switching network for a C chord. There are seven such networks for theseven common chords, these, in addition to the C chord, comprising Bb, F, C, G, D, A and E. Since the remaining chord sw itching networks are similar, only the chord switching network 256 for the C chord is shown. An input line 168 is provided at the bottom of the chord switching circuit which is directly connectedto the line 168 from FIG. 3. This line is connected to the fixed contacts of three single-pole singlethrow switches 258, 260 and 262, respectively corresponding to a C 7th chord, a C major chord and a C minor chord. v

The moveable switch contact 260 for the C major chord is connected to the anode of the diode 264 leading to a junction 266 and the anode of a series connected diode 268. The cathode of the diode 268 is connected to a tie point 270, indicated as a triangle and having the musical note G therein. The triangle 270, labeled as G, is directly conneeted to the G triangle tie point 254 of the diode matrix. Thus, whenevera positive potential is appliedto the line 168 with the switch 260 closed, the diodes 264 and 268 are open to supply a positive potential through the tie points to open the diodes 242 and 240 of the G tone to pass it through to the line 98.

. In addition, the switch 260 is connected from a junction 272 to a junction 274 which is connected to the anode of a diode 276 having its cathode connected to a tie point 270 labeled as E and directly connected to the E tie point 254. Furthermore, the junction 266 is con- I060ll 0170 nected to a junction 278 which is connected to the anode of a diode 280 having its cathode connected to the C tie point 270. Thus, when positive potential is applied by means of the line 168 and switch 260, positive potential is applied simultaneously to the C, E and G tie points, whereby to play a C major chord. The C 7th switch 258 is connected to a junction 282 and from thence to the anode of a diode 284 having its cathode connected to the junction 274. In addition, the junction 282 is connected to the anode of a diode 286 leading to the tie point 270. Thus, when the C 7th switch 258 is closed and a positive potential appears on the line 168 the At circuit will be open as well as the C, E and G circuits, whereby a C 7th chord will be played.

The C minor switch 262 is connected to a junction 288 leading to the anode 'of the diode 290 having its cathode connected to the junction 278. Likewise, the junction 288 is connected to the anode of the diode 292 leading to the Gil tie point 270.

Accordingly, when the C minor switch 262 is closed, and positive potential appears on the line 168, the circuits for C, G and G will be turned on, whereby to play a C minor chord.

As will be appreciated, the reference to appearance of positive potential on the line 168 is with regard to the circuit previously discussed in FIG. 3, whereby the positive potential comprises a series of pulses appearing in selected rhythm pattern.

A bass switching unit 294 is provided at the right side of FIG. 4. The bass switching circuit is provided with note oscillations as indicated at the squares 296 from the respective notes indicated therein, namely: E, A, D, G, C, F and B As will'be observed, these are the same notes as the chords that are to be played by the various chord switching networks 256. Each of the note input squares 296 is connected through a resistor 298 to a bass switch 300 which is in turn connected to a collector line 302. The collector line is connected to the line 80 comprising the bass input line 80 of FIG. 3, as previously described.

The physical arrangement of the bass switches and chord switches is not shown, since such physical arrangements are known in the art. However, it will be understood that the bass switches (which are normally open single-pole single-throw switches) are directly closable by manual actuators such as push buttons, with the push buttons preferably arranged in a horizontal row. The various chord switches (also normally open single-pole single throw switches) likewise are preferably operated by push buttons, and these push buttons are arranged in more or less vertical columns above the horizontal row of bass push buttons. For example, the push buttons for the C chord, which would comprise three buttons, respectively for the C major, C minor and C 7th chords would be in alignment with the C bass button. Thus, it is a simple matter to depress a desired bass button with the left thumb and the corresponding desired chord button with one of the left fingers, such as the index finger.

The chord and bass switching circuits of FIG. 4, are useful independently of the circuit of FIG. 3, to play the bass and chords in non-automatic fashion, as will be apparent with reference to FIG. 5. Much of FIG. is similar to parts of FIG. 3, being a simplification thereof, and similar parts are identified by like numerals with the addition of the suffix b. Thus, the bass signal input is applied to a line b leading to two transistor amplifier stages 84b and 85b comprising a driver circuit 82b, the output of which leads to a divider 86b.

The output of the divider 86b goes to a resistancecapacitance network 304 leading to a transistor amplifier stage 94b with the output thereof applied to a line 96b leading out to the straf units, amplifiers and loudspeaker system.

Similarly, the chord signal input from the chord switchboard is applied to a line 98b leading to a transistor amplifier stage 100b which has the output applied to the line 96b, just mentioned. As will be apparent, when the non-automatic circuit of FIG. 5, is to be used with FIG. 4, direct current would be applied continuously to the line 168 of FIG. 4. Thus, whenever a chord button is depressed, the chord is played as long as the button is held depressed. Similarly, since there is nothing to effect switching of the bass signal in the circuit of FIG. 5, as long as a bass push button is held down, the corresponding bass note will sound.

OPERATION When the apparatus as herein shown and described is set with the switch 136 in automatic'position, the bass drum pulse train will produce a pulse from the rhythm primary logic 12a and rhythm pattern gates 14a on the first beat for 3/4 time, or on the first and third beat for 4/4 time. This will cause the Schmitt trigger circuit to charge the capacitor 128 rapidly, discharge being through the resistor 132, and also through resistors 130, 114 and 134, to produce the wave shape or envelope 148. This wave shape in turn controls the opening of the diode gate 90 whereby to produce the bass signal as a decaying basis at beat 1, or beats l and 3, as just noted, the signal being divided by the divider 86 to lower the bass tone an octave, and subsequently being amplified by the transistor amplifier stage 94 and applied to the output line at 96.

At the same time, if either the march or Latin rhythm is turned on, the bass drum pulse train will also pass through the diodes 180, 192 or 182,194, respectively, to charge the capacitor 164 through the diode 162 by way of the Schmitt trigger circuit 152 to produce the envelope 170, which is applied to the chord switchboard to produce the chord simultaneously with the bass note on the first beat or on the first and third beats, as aforesaid.

Furthermore, depending upon how the switching is set as for march, swing, Latin or waltz, pulses will appear from the rhythm pattern No. 4, or from the block pulse train or from the cymbal pulse train, or some combination thereof, to supply pulses to the Schmitt trigger circuit 152 on the second and third beat of waltz time, or on the second and fourth beat for march time, and on other beats for swing and Latin. Obviously, a switch can be provided in the line 178 so that the bass drum pulse train will not pulse the chords.

According y, the bass may alternate with the chords or the chords may play at pulsed times along with the bass, and also independently of the bass. On the other hand, when the switch 136 is switched to manual, or if the circuit of FIG. 5 is used, the bass and the chords will play whenever an appropriate button is depressed, which may be continuously, or on an alternating basis if the player is sufficiently dextrous.

"is recognized that an on-off signal of the same intensity as a continuous signal sounds of lower intensity to the ear. Thus, when the apparatus is set for automatic operation, the level of the pulse delivered through the diode 126 to charge the capacitor 128 is very nearly at the 17.5 volt supply potential, since the collector resistor of the transistor 124 is of a much lower value than is the resistor 132, the two forming a voltage divider through the diode 126. On the other hand, .when the apparatus is set for manual operation, the voltage divider includes the resistor 150 which is of a much lower value than the resistor 132, and not a great deal larger than the collector resistor of the transistor 124. Thus, the potential applied through the diode 126 is much lower for the non-automatic or manual operation.

In addition to the'automatic operation of the bass and chords, if a stop switch to the pedal assembly of the organ is closed, a negative pulse will'appear on the line 226 whenever apedal is depressed, thus, providing a manually controllable production of the chord in addition to the automatic timed playing of the chord.

As has been noted heretofore, when the apparatus is set for automatic operation, and there is no bass signal in, the operation of the circuit 106 is such that the transistor 112 is conducting, whereby the junction between the resistors 130 and 148 is held substantially at ground potential, thereby to prevent any spurious The specific examples of the invention as herein shown and described will be understood as being illustrative only. Various changes in the structure will no doubt occur to those skilled in the art, and will be understood as forming a part of the present invention insofar as they fall within the spirit and scope of the appended claims.

The invention is claimed as follows:

I. Automatic rhythmic chord playing apparatus in an electronic organ, said organ having a plurality of keys and pedals and a plurality of means for generating tone oscillations corresponding to said keys and to said pedals and interconnected therewith, the means for producing tone oscillations corresponding to pedals comprising divider means connected to the generators for the tone oscillations corresponding to the keys comprising electronic gate means connected to the output of said divider means, means for rendering said electronic gate means conductive suddenly and for subsequently rendering said electronic gate means signals from opening or partially opening the diode gate gradually non-conductive, pulse producing means, means connectin'gsaid pulse producing means to said means for rendering said gate means conductive and non-conductive to pass oscillations corresponding to pedal tone'sin accordance with-a predetermined pattern, means connected to predetermined groups of said gate means and to said pulse producing means to pass oscillations corresponding to chords musically related to said pedal tones in accordance with the pattern of said pulses, said last named means comprising a plurality of normally non-conducting gates respectively receiving pulses'from said pulse producing means and having a common output line, means for respectively rendering said non-conducting gates conductive to transmit pulses to said common output. line, and pulse sha ing means eonnectingsaid common output line to san predetermined groups of gate means and output means connectedto said gatesand to said gate means and receiving the tone oscillations therefrom.

2. Automatic rhythmic chord playing apparatus in an electronic organ, said organ having a plurality of keys and pedals and a plurality of means for generating tone oscillations corresponding to said keys and to said pedals and interconnected therewith, comprising a plurality of electronic gates, means connecting said gates to said tone generators, means' for producing pulses corresponding to musical beats, means connecting said pulse producing means to certain of said gates to pass oscillations corresponding to pedal tones in accordance with a predetermined pattern including at least on the first musical beat of a measure, means connecting said pulse producing means to groupsof said gates to pass oscillations corresponding to chords musically related to said pedal tones on certain of said beats otherthan the first beat of a measure, means connected to the organ pedals and to said chord gates for rendering said chord gates conductive upon depression of any pedal, and output means connected to said gates and receiving the tone oscillations therefrom.

3. Apparatus as set forth in claim 1 including means for playing chords and pedal tones manually instead of automatically and including means for limiting the conductivity of the gate means to a lower level for manual than automatic operation to produce pedal tones at a lower intensity on manual operation than on automatic operation.

4. Apparatus as set forth in claim 1 wherein the means for respectively rendering the non-conducting gates conductive comprises DC.

i i l III l060ll 0172 

1. Automatic rhythmic chord playing apparatus in an electronic organ, said organ having a plurality of keys and pedals and a plurality of means for generating tone oscillations corresponding to said keys and to said pedals and interconnected therewith, the means for producing tone oscillations corresponding to pedals comprising divider means connected to the generators for the tone oscillations corresponding to the keys comprising electronic gate means connected to the output of said divider means, means for rendering said electronic gate means conductive suddenly and for subsequently rendering said electronic gate means gradually nonconductive, pulse producing means, means connecting said pulse producing means to said means for rendering said gate means conductive and non-conductive to pass oscillations corresponding to pedal tones in accordance with a predetermined pattern, means connected to predetermined groups of said gate means and to said pulse producing means to pass oscillations corresponding to chords musically related to said pedal tones in accordance with the pattern of said pulses, said last named means comprising a plurality of normally non-conducting gates respectively receiving pulses from said pulse producing means and having a common output line, means for respectively rendering said non-conducting gates conductive to transmit pulses to said common output line, and pulse shaping means connecting said common output line to said predetermined groups of gate means and output means connected to said gates and to said gate means and receiving the tone oscillations therefrom.
 2. Automatic rhythmic chord playing apparatus in an electronic organ, said organ having a plurality of keys and pedals and a plurality of means for generating tone oscillations corresponding to said keys and to said pedals and interconnected therewith, comprising a plurality of electronic gates, means connecting said gates to said tone generators, means for producing pulses corresponding to musical beats, means connecting said pulse producing means to certain of said gates to pass oscillations corresponding to pedal tones in accordance with a predetermined patTern including at least on the first musical beat of a measure, means connecting said pulse producing means to groups of said gates to pass oscillations corresponding to chords musically related to said pedal tones on certain of said beats other than the first beat of a measure, means connected to the organ pedals and to said chord gates for rendering said chord gates conductive upon depression of any pedal, and output means connected to said gates and receiving the tone oscillations therefrom.
 3. Apparatus as set forth in claim 1 including means for playing chords and pedal tones manually instead of automatically and including means for limiting the conductivity of the gate means to a lower level for manual than automatic operation to produce pedal tones at a lower intensity on manual operation than on automatic operation.
 4. Apparatus as set forth in claim 1 wherein the means for respectively rendering the non-conducting gates conductive comprises DC. 